A thermochromic pigment can be used as a reversible low temperature thermochromic paint in which colors change at a temperature of 50 to 70° C. It has a principle of a material inside a microcapsule dispersing and becoming transparent as a temperature increases, and returning to its original color by aggregation as the temperature decreases, however, the use for high-temperature range heating products or high-frequency heating has been limited since the capsule is destroyed and gas is generated when the capsule is heated to 300° C. or higher. In addition, pigments of red, yellow and orange colors, which are made of cadmium, have a property of their color changing to black at 150 to 200° C., however, the use for cooking container interiors has been limited due to the toxic properties of heavy metals.
Meanwhile, Korean Patent Application Laid-Open Publication No. 10-2012-0052326 discloses a reversible thermochromic water-based ink composition made of an organic nitrogen sulfur compound and an aqueous resin, wherein the organic nitrogen sulfur compound is at least one type of compounds selected from the group consisting of 2-(4-thiazoyl)-benzimidazole, 2-(thiocyanatemethylthio)-1,3-benzothiazole, 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one. However, the invention does not disclose a temperature-sensitive plate, which is described in the present invention.
As a result, in order to remedy the shortcomings and problems of existing technologies, the present inventors invented a reversible thermochromic ceramic coating agent in which colors change depending on temperatures by absorbing (absorption and radiation are equivalent) all the light from a near infrared region, and which has heat resistance of 400° C. or higher and durability.
An object of the present invention is to provide a reversible color changeable coating composition and a preparation method thereof by grinding a silica sol, Fe2O3 or additional compounds as a pigment and filler using a ball mill in order to prepare a reversible thermochromatic ceramic coating agent in which colors change from a low temperature around 100° C., and which has heat resistance of 400° C. or higher and durability.
In addition, another object of the present invention is to provide a plate that comprises the composition and a method for changing colors using this plate.